Where can I find this?

I have been plumbing for over 25 years. I have run across these stainless steel kitchen sinks a number of times. This is the first time I have needed to replace the drain on one. they don’t take your normal basket strainer assembly but do use a regular basket strainer plug. The sink itself drops down into a cup at the drain very similar to the cup on the basket strainer and just has the Center piece of the basket strainer in it. I have no idea what they are called. Can anyone tell me where I could get a replacement one?